The immediate aim of the proposed research is to develop a useful and informative animal model of need for alcohol. Need is defined in terms of how the subject adapts to an increase in cost of alcohol. For example, if behavior increases when the cost of an item increases then the subject has revealed a need for the item. In contrast, a dispensable good or reinforcer will be avoided if its cost increases. Put somewhat differently, behavior that returns the level of alcohol consumption towards its pre-restricted or less expensive level defines need for alcohol. By this criterion, a preliminary study showed that rats developed a need for alcohol. The proposed studies evaluate factors that are likely to engender and maintain alcohol need. These include drinking history, for example amount per bout and number of bouts, and the magnitude and frequency of competing reinforcers. In addition, several of the experiments seek more precise ways of measuring need for alcohol. The studies share a common strategy. First the rat is induced to drink large amounts of alcohol (e.g., more than 3 to 4 g/kg per session) over a long period of time (e.g., 80 sessions), and then it is tested for alcohol need by making the alcohol less available. A serious methodological problem is that the study requires the rats to voluntarily drink alcohol, but rats learn to avoid alcohol or by the sucrose. For example, in one of the preliminary studies it was shown that preference for alcohol was independent of its caloric value. In the long term, it is hoped that this research will contribute to our understanding of addiction, especially alcoholism.